Indonesia is preparing for a possible eruption of the Anak Krakatau, which caused a tsunami that already killed at least 430 people.
Indonesian authorities have warned that the crater of Anak Krakatau volcano remains fragile, raising fears of another collapse and tsunami. Accordingly, they have upped the alert level and ordered all flights to steer clear of the area.
The volcano has been particularly active since Sunday, spewing lava and rocks, and sending huge clouds of ash up to 3,000 meters into the sky. The Geological Agency of Indonesia (GAI), in raising the alert level to the second-highest, effected a five-kilometer exclusion zone around the island.
"Since Dec. 23, activity has not stopped... We anticipate a further escalation," Antonius Ratdomopurbo, secretary of the GAI, said.
A thin layer of volcanic ash has been settling on buildings, vehicles and vegetation along the west coast of Java since late Wednesday.
"All flights are rerouted due to Krakatau volcano ash on red alert," Indonesia's air traffic control agency AirNav added in a release.
The volcano's eruption on Dec. 22 caused the collapse of its southwest slope, which fell into the sea and caused a tsunami that struck the west coast of Java and south of Sumatra.
Rescue teams are still working but with little hope of finding any remaining survivors of the disaster, which caused 430 deaths, 1,495 injuries and left 159 people missing, according to the latest official assessment.
The tsunami also forced about 22,000 people to flee to evacuation centers.
Indonesia is located over the Pacific's Ring of Fire, an area of great seismic and volcanic activity that is shaken every year by some 7,000 mostly moderate earthquakes.
In 1883, the Krakatoa volcano erupted in one of the biggest blasts, in recorded geological history, killing more than 36,000 people.
Although the volcano disappeared under the sea and remained inactive for decades, the Krakatoa generated the Anak Krakatau island through eruptions that occurred between 1928 and 1930.
The Anak Krakatau, which means 'Child of Krakatoa' in the Indonesian language, has been growing ever since at a rate of five meters per year.